I have an XC540 roland PC machine. When cutting a laminated sheet with crop marks, the first crop mark is detected, then as the sensor is moving to detect the left mark, it feeds away from me a few mm every 2 seconds or so. By the time the sensor is at the second mark, it's nearly under the pinch roller. It works if I purposely miss align the left crop mark toward me by about 3/4". Any ideas? Cheers from Nova Scotia. Thanks in advance.